The present invention relates to a half mirror film forming method in which a half mirror film is formed on a substrate, and to an optical member provided with a half mirror film.
Heretofore, such as an optical substrate or an optical film and an optical lens have been known as parts having a half mirror film on a substrate having a light transmissive property. For example, an optical substrate and an optical film have been utilized in electro-optical equipment such as a semi transmissive type liquid crystal display device, a spatial optical modulation device, and an optical lens in various applications such as an optical element for laser.
As a method to prepare a half mirror film having light transmissive property, is known a coating method in which materials to form a half mirror film being dissolved in suitable solvents are provided by dipping or coating, or a vacuum evaporation method.
However, in a coating method, uniformity of film thickness or optical functions is not necessarily sufficient and durability level is neither satisfactory. Further, in a vacuum evaporation method, the productivity is low since the number of sheets of an optical substrate or an optical film loaded in a evaporation chamber at once is extremely small, in addition, there is also a problem of poor adhesion with a half mirror film in case of a resin substrate because a heating vacuum evaporation method cannot be applied, which may cause a half mirror film being easily cracked.